1. Field of the Invention
This invention relates to non-agglomerated, free-flowing, vitamin powders containing a coating of hydrophobic silica.
2. Description of the Prior Art
Heretofore, agglomerated vitamin-containing powders have been prepared containing a coating of an absorbent material such as silicic acid by spray-drying a mixture of an aqueous vitamin slurry or emulsion in the presence of such a dry particulate absorbent material. Examples of such powders are disclosed in U.S. Pat. No. 3,962,384; U.S. Pat. No. 3,959,472; U.S. Pat. No. 3,947,596; and U.S. Pat. No. 3,914,430.
It is conventional to spray-dry combinations of a medicament and a water-insoluble carrier such as calcium sulfate and dicalcium phosphate in the presence of a retarding agent so as to obtain solid, sustained release, pharmaceutical preparations, as disclosed in U.S. Pat. No. 3,632,739.
Vitamin-containing aqueous colloid beads have been prepared utilizing an aqueous solution of gelatin as an encapsulating agent. The aqueous gelatin coating around the vitamin is formed by spraying droplets of the aqueous gelatin-vitamin mixture into a cooling tower and collecting at the base of the tower in admixture with the resulting powder a water-absorbing powder such as powdered silica gel. The gelatin-coated vitamin is thereafter separated from the water-absorbing powder, as disclosed in U.S. Pat. No. 3,445,563.
The vitamin-containing powders of the prior art can be improved in free-flowing properties by spray-drying droplets of vitamin and encapsulating agent containing a water-insoluble carrier in the presence of a hydrophobic silica.